Sheet post-processing apparatus

A sheet post-processing apparatus which receives a sheet having an image formed thereon, that is discharged from an image forming apparatus according to page order, comprising:

• first and second discharge trays being provided in a number of at least two;
• a first transport path for guiding to said first discharge tray the sheet having an image formed thereon discharged through a sheet discharge opening of said image forming apparatus;
• a branched transport path being branched from said first transport path;
• a second transport path connected to said branched transport path, for guiding the sheet having an image formed thereon to said second discharge tray;
• sheet transport means for transporting a sheet being transported in each transport path between a normal direction and a reverse direction, wherein said sheet transport means includes:
• first transport rollers for discharging the sheet to said first discharge tray, which permits a transport direction of the sheet to be reversed, said first transport rollers being formed along said first transport path,
• second transport rollers for discharging a sheet to said second discharge tray, which permits the transport direction of the sheet to be reversed, said second transport rollers being formed along said second transport path, and
• third transport rollers for transporting the sheet in said branched transport path and permitting the transport direction of the sheet to be reversed;
• and
• a transport path switching member for switching the transport path for the sheet, said transport path switching member being provided at a junction between said first transport path and said branched transport path.

A post-processing apparatus which reverses a sheet having an image formed thereon, that is discharged from an image forming apparatus according to page order, comprising:

• first and second discharge trays being provided in a number of at least two;
• a first transport path for guiding the sheet having an image formed thereon discharged through a sheet discharge opening of said image forming apparatus to said first discharge tray;
• a branched transport path being branched from said first transport path;
• a second transport path connected to said branched transport path, for guiding the sheet having an image formed thereon to said second discharge tray;
• sheet transport means for transporting a sheet being transported in each transport path both in a normal direction and a reverse direction;
• a transport path switching member for switching a transport path of the sheet, said transport path switching member being provided at least at a junction between said first transport path and said branched transport path;
• and
• control means for controlling said sheet transport means and said transport path switching member in such a manner that a sheet being transported through said first and second transport paths is discharged onto respective discharge trays without being reversed, while reversed sheets are discharged onto respective discharge trays by utilizing said first and second transport paths as a switch back transport path by reversing the transport direction of the sheet by said sheet transport means, and that sheets are discharged onto the discharge tray as selected according to an image forming mode set in said image forming apparatus.

A sheet post-processing apparatus which receives a sheet having an image formed thereon, that is discharged from an image forming apparatus according to page order, comprising:

• first and second discharge trays being provided in a number of at least two;
• a first transport path for guiding to said first discharge tray the sheet having an image formed thereon discharged through a sheet discharge opening of said image forming appratus;
• a branched transport path being branched from said first transport path;
• a second transport path connected to said branched transport path, for guiding the sheet having an image formed thereon to said second discharge tray, said second transport path being connected to a retransport path that is used when said image forming apparatus carries out a double-sided copying operation or a composite copying operation;
• sheet transport means for transporting a sheet being transported in each transport path both in a normal direction and a reverse direction, wherein said sheet transport means includes:
• first transport rollers for discharging the sheet to said first discharge tray, which permits a transport direction of the sheet to be reversed, said first transport rollers being formed along said first transport path,
• second transport rollers for discharging a sheet to said second discharge tray, which permits the transport direction of the sheet to be reversed, said second transport rollers being formed along said second transport path, and
• third transport rollers for transporting the sheet in said branched transport path and permitting the transport direction of the sheet to be reversed;
• transport path switching members for switching a sheet transport path, said transport path switching members being provided at a junction between said first transport path and said branched transport path, and a junction between said second transport path and said branched transport path;
• and
• control means for controlling said sheet discharge means and said transport path switching members in such a manner that a sheet is fed into said retransport path so that a next image is formed on the back surface of the surface on which the previous image is formed when said image forming apparatus carries out a double-sided copying operation, while a sheet is fed into said retransport path so that the next image is formed on the surface whereon the previous image is formed when said image forming apparatus carries out a composite copying operation on the same surface of the sheet.

A sheet post-processing apparatus which receives a sheet having an image formed thereon, that is discharged from an image forming apparatus according to page order, comprising:

• first and second discharge trays being provided in a number of at least two;
• a first transport path for guiding to said first discharge tray the sheet having an image formed thereon discharged through a sheet discharge opening of said image forming apparatus;
• a second transport path formed so as to face said first transport path, for guiding the sheet having an image formed thereon to said second discharge tray;
• a branched transport path for connecting said first transport path and said second transport path;
• sheet transport means for transporting a sheet being transported in each transport path between a normal direction and a reverse direction;
• a transport path switching member for switching the transport path of the sheet, said transport path switching member being provided at a junction between said first transport path and said branched transport path;
• and
• control means for controlling said sheet transport means and said transport path switching member in such a manner that a sheet transported through said first and second transport path is discharged onto respective discharge trays without being reversed, while a reversed sheet is discharged onto each discharge tray utilizing said first and second transport paths as a switch back transport path by reversing a transport direction of a sheet being transported by said sheet transport means, and that the sheet is discharged onto the discharge tray as selected according to an input device for inputting image data when said image forming apparatus performs an image forming operation.